1. Field of the Disclosure
The present disclosure relates to radio frequency (RF) communication technology, and more specifically to an RF device based on Band 28 and a communication method thereof.
2. Description
At present, the third Generation Partnership Project (3GPP) divides Band 28 (hereinafter referred as B28) into RX=758M-803 MHz and TX=703M-748 MHz. However, Band 28 and band of Digital Television (DTV) are very close, and lead an overlapping band. Shown as FIG. 1, B28_UL is for an uplink band, UL (uplink) means TX (transmit). B28_DL is for a downlink band, DL (downlink) means RX (receive). B20, B26, and B28 are different bands. In a Japanese band (JP) shown in FIG. 1, an overlap part between band of the DTV and the uplink band of B28 (B28_UL) is 703 MHz-710 MHz (shown as A). In an European Union band (EU), the overlap part of the downlink band of B28 (B28_DL) and the downlink band of B20 (B28_DL) is 791 MHz-803 MHz (shown as B). Due to large transmission power, noise interference that produced easily, the uplink band needs to suppress the overlap band. Meanwhile, whether the downlink band overlaps or not does not affect the transmission of the data.
Nowadays, common platforms all support full band of Band 28. Concerning operating costs, most terminal manufacturers produce mobile phones in the full band of Band 28. However, there is a very important testing item, called additional spectrum stray. In order to solve coexistence between band of DTV and B28, suppression ability of duplexes for B28 is particularly important in the range from 703 MHz to 710 MHz. And from March 2015, the additional spectrum stray of B28 has been listed as a default item by the certification body. Especially, upon a condition that 5M and 10M of NS-17 is bandwidth measured, the measured frequencies needs E-URA fall into the range from 718 MHz to 748 MHz, the test frequency points are 725.5 MHz (corresponding to the 5M) and 723 MHz (corresponding to the 10M).
As a radio frequency (RF) architecture shown in FIG. 2, an uplink band of the duplexer is 703 MHz-748 MHz, an overlap part covered band of the DTV is 703 MHz-710 MHz. upon a condition that the measure sweep band is 470M Hz-710 MHz, and the 470 MHz-710 MHz falls into Band 28, the duplexer cannot suppress for the range from 703 MHz to 710 MHz (if suppressed, the data of the frequency will be lost). Therefore, upon a condition that using the traditional RF test solution, the additional spectrum stray is very hard to implement because the overlap part cannot be suppressed.
Therefore, the prior art has to be improved and developed.